/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.support.lob;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;
import java.nio.charset.StandardCharsets;
import java.sql.Clob;
import java.sql.SQLException;

import org.springframework.lang.Nullable;
import org.springframework.util.FileCopyUtils;
import org.springframework.util.StreamUtils;

/**
 * Simple JDBC {@link Clob} adapter that exposes a given String or character stream.
 * Optionally used by {@link DefaultLobHandler}.
 *
 * @author Juergen Hoeller
 * @since 2.5.3
 */
class PassThroughClob implements Clob {

    @Nullable
    private String content;

    @Nullable
    private Reader characterStream;

    @Nullable
    private InputStream asciiStream;

    private long contentLength;


    public PassThroughClob(String content) {
        this.content = content;
        this.contentLength = content.length();
    }

    public PassThroughClob(Reader characterStream, long contentLength) {
        this.characterStream = characterStream;
        this.contentLength = contentLength;
    }

    public PassThroughClob(InputStream asciiStream, long contentLength) {
        this.asciiStream = asciiStream;
        this.contentLength = contentLength;
    }


    @Override
    public long length() throws SQLException {
        return this.contentLength;
    }

    @Override
    public Reader getCharacterStream() throws SQLException {
        if (this.content != null) {
            return new StringReader(this.content);
        } else if (this.characterStream != null) {
            return this.characterStream;
        } else {
            return new InputStreamReader(
                    (this.asciiStream != null ? this.asciiStream : StreamUtils.emptyInput()),
                    StandardCharsets.US_ASCII);
        }
    }

    @Override
    public InputStream getAsciiStream() throws SQLException {
        try {
            if (this.content != null) {
                return new ByteArrayInputStream(this.content.getBytes(StandardCharsets.US_ASCII));
            } else if (this.characterStream != null) {
                String tempContent = FileCopyUtils.copyToString(this.characterStream);
                return new ByteArrayInputStream(tempContent.getBytes(StandardCharsets.US_ASCII));
            } else {
                return (this.asciiStream != null ? this.asciiStream : StreamUtils.emptyInput());
            }
        } catch (IOException ex) {
            throw new SQLException("Failed to read stream content: " + ex);
        }
    }


    @Override
    public Reader getCharacterStream(long pos, long length) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public Writer setCharacterStream(long pos) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public OutputStream setAsciiStream(long pos) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public String getSubString(long pos, int length) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public int setString(long pos, String str) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public int setString(long pos, String str, int offset, int len) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public long position(String searchstr, long start) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public long position(Clob searchstr, long start) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public void truncate(long len) throws SQLException {
        throw new UnsupportedOperationException();
    }

    @Override
    public void free() throws SQLException {
        // no-op
    }

}
